Fire timing control in printing devices

Abstract

Some of the embodiments of the present disclosure provide a method for generating each of (i) a first signal and (ii) a second signal based at least in part on a position of a carriage, where the carriage is a component of a printing device, estimating (i) a major cycle duration associated with the first signal and (ii) a first minor cycle duration associated with the second signal, estimating a position of the carriage based at least in part on the estimated major cycle duration and the estimated first minor cycle duration, and generating a plurality of print synchronization pulses based at least in part on the estimated position of the carriage.

The invention claimed is: 
     
       1. A printing device comprising:
 a carriage configured to traverse over a printing medium;
 a sensor attached to the carriage, wherein the sensor is configured to traverse over the printing medium along with the carriage, and wherein the sensor is configured to, based on the traversal of the carriage over the printing medium, generate a first signal and a second signal; 
 
 a velocity and acceleration estimation unit configured to estimate, based on both the first signal and the second signal, a velocity of the carriage; 
 a distance accumulation unit configured to, based on the estimated velocity of the carriage, estimate a position of the carriage as the carriage is being traversed over the printing medium; 
 a print synchronization pulse generation unit configured to, based on the estimated position of the carriage, generate a stream of print synchronization pulses at a predetermined rate; and 
 a printing head mounted on the carriage, wherein the printing head is configured to eject a printing substance on the printing medium in synchronization with each print synchronization pulse of the stream of print synchronization pulses, 
 wherein the print synchronization pulse generation unit comprises
 a time of flight error compensation unit configured to, in response to a change in the estimated velocity of the carriage as the carriage is being traversed over the printing medium, adjust the predetermined rate at which the stream of print synchronization pulses are generated to compensate for the change in the estimated velocity of the carriage as the carriage is being traversed over the printing medium. 
 
 
     
     
       2. The printing device of  claim 1 , wherein the time of flight error compensation unit is configured to adjust the predetermined rate at which the stream of print synchronization pulses are generated by:
 selectively modifying a timing of generation of one or more print synchronization pulses of the stream of print synchronization pulses. 
 
     
     
       3. The printing device of  claim 1 , wherein the sensor comprises:
 a light emitting element including (i) a first light emitting section configured to emit light, and (ii) a second light emitting section configured to emit light; and 
 a light receiving element including (i) a first light receiving section configured to selectively receive light from the first light emitting section based on the traversal of the carriage over the printing medium, and (ii) a second light emitting section configured to selectively receive light from the second light emitting section based on the traversal of the carriage over the printing medium, 
 wherein based on light received by the first light receiving section from the first light emitting section, the sensor is configured to generate the first signal, and 
 wherein based on light received by the second light receiving section from the second light emitting section, the sensor is configured to generate the second signal. 
 
     
     
       4. The printing device of  claim 3 , further comprising:
 a slit tape having a plurality of slits arranged in regular intervals along the slit tape, 
 wherein as the sensor is being traversed over the printing medium along with the carriage, (i) light from the first light emitting section is received by the first light receiving section when the first light emitting section and the first light receiving section are aligned through a slit of the plurality of slits, and (ii) light from the first light emitting section is not received by the first light receiving section when the first light emitting section and the first light receiving section are not aligned through any slit of the plurality of slits. 
 
     
     
       5. The printing device of  claim 3 , further comprising:
 a slit tape having a plurality of slits arranged in regular intervals along the slit tape, 
 wherein as the sensor is being traversed over the printing medium along with the carriage, (i) light from the first light emitting section is received by the first light receiving section through one or more of the plurality of slits, and (ii) light from the second light emitting section is received by the second light receiving section through one or more of the plurality of slits. 
 
     
     
       6. The printing device of  claim 1 , further comprising:
 a cycle duration estimation unit configured to
 receive (i) the first signal, and (ii) the second signal, 
 estimate a first cycle duration associated with the first signal, wherein the first cycle duration corresponds to a time duration between one of (i) a last two rising edges of the first signal, or (ii) a last two falling edges of the first signal, and 
 estimate a second cycle duration associated with the second signal, wherein the second cycle duration corresponds to a time duration between one of (i) a last two rising edges of the second signal, or (ii) a last two falling edges of the second signal, 
 
 wherein the velocity and acceleration estimation unit is configured to estimate the velocity of the carriage and the acceleration of the carriage based on (i) the first cycle duration associated with the first signal, and (ii) the second cycle duration associated with the second signal. 
 
     
     
       7. The printing device of  claim 6 , wherein the cycle duration estimation unit is further configured to:
 estimate a third cycle duration associated with the first signal, wherein the third cycle duration corresponds to a time duration between another of (i) the last two rising edges of the first signal, or (ii) the last two falling edges of the first signal, and 
 estimate a fourth cycle duration associated with the second signal, wherein the fourth cycle duration corresponds to a time duration between another of (i) the last two rising edges of the second signal, or (ii) the last two falling edges of the second signal, 
 wherein the velocity and acceleration estimation unit is configured to estimate the velocity of the carriage and the acceleration of the carriage based on (i) the first cycle duration associated with the first signal, (ii) the second cycle duration associated with the second signal, (iii) the third cycle duration associated with the first signal, and (iv) the fourth cycle duration associated with the second signal. 
 
     
     
       8. The printing device of  claim 7 , wherein the velocity and acceleration estimation unit is further configured to estimate the acceleration of the carriage such that the estimated acceleration is substantially equal to (Aa*ta+Ba*tb+Ca*tc+Da*td), wherein ta, tb, tc, and td are the first cycle duration, the second cycle duration, the third cycle duration, and the fourth cycle duration, respectively, and wherein Aa, Ab, Ac, and Ad are acceleration weighting coefficients. 
     
     
       9. The printing device of  claim 6 , wherein the print synchronization pulse generation unit is further configured to generate a plurality of print synchronization pulses during the first cycle duration, such that the plurality of print synchronization pulses are generated substantially uniformly across a distance traversed by the carriage during the first cycle duration. 
     
     
       10. The printing device of  claim 9 , wherein the print synchronization pulse generation unit is further configured to generate, responsive to a change in the estimated velocity of the carriage during the first cycle duration, the plurality of print synchronization pulses in non-uniform time intervals to compensate for the change in the estimated velocity of the carriage during the first cycle duration. 
     
     
       11. The printing device of  claim 1 , wherein the velocity and acceleration estimation unit is further configured to:
 estimate, based on the first signal and the second signal, (i) an initial velocity of the carriage, and (ii) an acceleration of the carriage; and 
 based on the initial velocity of the carriage and the acceleration of the carriage, estimate the velocity of the carriage. 
 
     
     
       12. The printing device of  claim 1 , wherein the printing device is an inkjet printer, and wherein the printing substance comprises ink. 
     
     
       13. A method for adjusting a predetermined rate at which a print head, mounted on a carriage, ejects a printing substance onto a printing medium as the carriage is being traversed over the printing medium, the method comprising:
 based on the traversal of the carriage over the printing medium, generating, by a sensor attached to the carriage, (i) a first signal, and (ii) a second signal; 
 based on the first signal and the second signal, estimating a velocity of the carriage; 
 based on the estimated velocity of the carriage, estimating a position of the carriage as the carriage is being traversed over the printing medium; 
 based on the estimated position of the carriage, generating a stream of print synchronization pulses at a predetermined rate, 
 wherein the print head is configured to eject the printing substance on the printing medium in synchronization with each print synchronization pulse of the stream of print synchronization pulses, and 
 wherein the method further comprises
 in response to a change in the estimated velocity of the carriage as the carriage is being traversed over the printing medium, adjusting the predetermined rate at which the stream of print synchronization pulses are generated to compensate for the change in the estimated velocity of the carriage as the carriage is being traversed over the printing medium. 
 
 
     
     
       14. The method of  claim 13 , wherein adjusting the predetermined rate at which the stream of print synchronization pulses are generated comprises:
 selectively modifying a timing of generation of one or more print synchronization pulses of the stream of print synchronization pulses. 
 
     
     
       15. The method of  claim 13 , wherein the sensor comprises:
 a light emitting element including (i) a first light emitting section configured to emit light, and (ii) a second light emitting section configured to emit light; and 
 a light receiving element including (i) a first light receiving section configured to selectively receive light from the first light emitting section, and (ii) a second light emitting section configured to selectively receive light from the second light emitting section, 
 wherein generating, by the sensor attached to the carriage, (i) the first signal, and (ii) the second signal comprises
 (i) based on light received by the first light receiving section from the first light emitting section, generating the first signal, and (ii) based on light received by the second light receiving section from the second light emitting section, generating the second signal. 
 
 
     
     
       16. The method of  claim 13 , further comprising:
 estimating a first cycle duration associated with the first signal, wherein the first cycle duration corresponds to a time duration between one of (i) a last two rising edges of the first signal, or (ii) a last two falling edges of the first signal; 
 estimating a second cycle duration associated with the second signal, wherein the second cycle duration corresponds to a time duration between one of (i) a last two rising edges of the second signal, or (ii) a last two falling edges of the second signal, 
 wherein estimating the velocity of the carriage further comprises
 based on (i) the first cycle duration associated with the first signal, and (ii) the second cycle duration associated with the second signal, estimating the velocity of the carriage. 
 
 
     
     
       17. The method of  claim 16 , further comprising:
 estimating a third cycle duration associated with the first signal, wherein the third cycle duration corresponds to a time duration between another of (i) the last two rising edges of the first signal, or (ii) the last two falling edges of the first signal; and 
 estimating a fourth cycle duration associated with the second signal, wherein the fourth cycle duration corresponds to a time duration between another of (i) the last two rising edges of the second signal, or (ii) the last two falling edges of the second signal, 
 wherein estimating the velocity of the carriage further comprises
 based on (i) the first cycle duration associated with the first signal, (ii) the second cycle duration associated with the second signal, (iii) the third cycle duration associated with the first signal, and (iv) the fourth cycle duration associated with the second signal, estimating the velocity of the carriage. 
 
 
     
     
       18. The method of  claim 17 , further comprising:
 estimating an acceleration of the carriage such that the estimated acceleration is substantially equal to (Aa*ta+Ba*tb+Ca*tc+Da*td), wherein ta, tb, tc, and td are the first cycle duration, the second cycle duration, the third cycle duration, and the fourth cycle duration, respectively, and wherein Aa, Ab, Ac, and Ad are acceleration weighting coefficients. 
 
     
     
       19. The method of  claim 15 , wherein generating the stream of print synchronization pulses further comprises:
 generating the stream of print synchronization pulses such that (i) a plurality of print synchronization pulses are generated during the first cycle duration, and (ii) the plurality of print synchronization pulses are generated substantially uniformly across a distance traversed by the carriage during the first cycle duration. 
 
     
     
       20. The method of  claim 19 , wherein, responsive to a change in the estimated velocity of the carriage during the first cycle duration, the plurality of print synchronization pulses are generated in non-uniform time intervals to compensate for the change in the estimated velocity of the carriage during the first cycle duration.